• Fracturing Bioprosthetic THVs Shows Increased Mortality Risk, ‘Modest’ Hemodynamic Benefit, in ViV TAVR – Analysis

    BOSTON — Fracturing balloon-expandable bioprosthetic transcatheter heart valves (THVs) was associated with an early risk of in-hospital mortality, especially when performed before valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR), a new registry analysis shows.

    The technique also showed only modest differences in hemodynamics, said Santiago Garcia, MD, of The Christ Hospital, Cincinnati, who presented these findings Sunday at Transcatheter Cardiovascular Therapeutics (TCT) 2022 in Boston.

    The use of bioprosthetic valves in aortic valve replacement procedures roughly tripled between 1998 and 2010 and exceeded that of mechanical valves in 2004.

    While bioprosthetic valves avoid the risks associated with lifelong anticoagulation that come with mechanical valves, he added, bioprosthetic valves are subject to structural deterioration.

    Valve-in-valve (VIV) TAVR has emerged as an alternative to surgical redo of aortic valve replacement. The number of ViV TAVR procedures has increased more than 10 times, from 410 in 2014 to 4,480 in 2019, and now represents about 6% of commercial TAVR cases in the U.S., Garcia said.

    However, he added, patient-prosthesis mismatch is an important limitation of ViV TAVR procedures.

    BVF is an intentional disruption of the stent frame of the transcatheter heart valve (THV) and has the potential to increase THV expansion and improve hemodynamics. Garcia said most, but not all, valves can be fractured.

    Even though knowledge has increased in recent years, there are still knowledge gaps, he said. Unanswered questions include which patients need BVF, when BVF should be performed and how to define success. Garcia said the current experience is limited to small observational studies, limited and selected sites and lack of a control group.

    The objective of the current study was to compare the safety and efficacy of ViV TAVR with or without BVF.

    Therefore, Garcia and several other investigators analyzed patients who underwent ViV TAVR with the balloon-expandable SAPIEN 3 or Ultra THV (Edwards Lifesciences) between December 2020 and March 2022 and were recorded in the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy (STS/ACC TVT) Registry.

    The investigators compared attempted and not-attempted BV, and whether BVF was attempted before or after ViV TAVR.

    The safety outcome was all-cause in-hospital mortality, and the hemodynamic outcomes were echocardiographic aortic valve area and mean gradient.

    A total of 2,975 patients underwent ViV TAVR. Of these, BVF was attempted in 619 (21%) and not attempted in 2,356 (79%). Of those in whom BVF was attempted, the attempt was before valve implantation in 141 patients (23%) and post-implantation in 466 (75%).

    Only 1,085 patients were included in the echocardiographic outcomes because these were the only ones for whom the true internal diameter of the THV was known. In this group, BVF was attempted in 250 patients (23%) and not attempted in 835 (77%). BVF was attempted pre-implant in 55 (22%) and post-implant in 189 (76%).

    An inverse probability of treatment weighting (IPTW) analysis showed that the all-cause mortality rate favored no BVF (odds ratio [OR]: 2.51; 95% confidence interval [CI] 1.30, 4.84; p<0.01). This was also true of cardiac death (OR 2.47; 95% CI 1.13, 5.39; p=0.02), the composite of all-cause mortality or stroke (OR 1.94; 95% CI 1.13, 3.33; p=0.02) and life-threatening bleeding (OR 2.55; 95% CI 1.44, 4.50; p<0.01).

    Turning to echocardiographic outcomes, mean aortic valve area and mean valve gradient both statistically significantly favored BVF, but the clinical difference was “modest,” Garcia said. Aortic valve area was 1.6 cm2 at discharge in the BVF group and 1.4 cm2 in the no-BVF group (p<0.01) at discharge, while mean valve gradient was 16.3 mm Hg in the BVF group and 19.2 mm Hg in the no-BVF group at discharge (p<0.01), a difference that slightly widened at 30 days (BVF 18.2 mm Hg, no-BVF 22.0 mm Hg; p<0.01).

    In the pre-implant BVF IPTW analysis, all-cause mortality and cardiac mortality again favored the no-BVF group (all-cause mortality: OR 2.90, 95% CI [1.21, 6.94], p=0.02; cardiac death: OR 3.42, 95% CI [1.25, 9.37], p=-0.02. While there was no significant difference between BVF and no-BVF in the post-implant timing analysis, the trends were in the direction of favoring no-BVF, Garcia said.

    Mean valve gradient among patients in the pre-implant timing was significantly lower at discharge (BVF 15.6 mm Hg vs. no-BVF 18.3 mm Hg; p=0.01), but this difference disappeared by 30 days (BVF 17.2 mm Hg vs. no-BVF 19.2 mm Hg; p=0.20). But post-implant timing showed that the significance stayed from discharge (BVF 16.4 mm Hg vs. no-BVF 19.4 mm Hg; p<0.01) to 30 days (BVF 18.3 mm Hg vs. no-BVF 22.6 mm Hg; p<0.01).

    Even so, these differences are modest, Garcia said, and are far less than previously reported. He added that the long-term risk of BVF needs to be further characterized and that there is an opportunity to standardize BVF indications, technique and post-procedural management.

    Image Credit: Jason Wermers/CRTonline.org

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